The number of calories you burn in a day depends on when you eat your food

Do you sleep at odd hours and have meals at irregular times during the day? Turns out, if you want to lose a lot of weight, you’ll need to follow a proper sleeping schedule and eat at normal hours. According to a study in the journal CurrentBiology, the number of calories that you burn while at rest may change, depending on the time of day.

The link between your circadian clock and metabolism

The results of the study revealed that when people are at rest, they burn 10 percent more calories in the late afternoon and early evening compared to the early morning hours. According to researchers, this highlights the importance of the circadian clock in governing metabolism. It could also explain why irregularities in eating and sleeping schedules because of shift work or other factors can make a person more likely to gain weight.

Kirsi-Marja Zitting, the lead author of the paper from the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital and Harvard Medical School, explained that the team was surprised to discover that doing the same thing at a certain time of day can burn more calories than doing it at a different time.

The team of scientists observed seven participants in a special laboratory to verify any changes in metabolism over the course of the day, apart from the effects of activity, sleep-wake cycle, and diet. The volunteers did not have access to clocks, the internet, their phones, or windows, so they had no idea what time it was outside.

The participants were assigned times to go to bed and wake up. Every night, the researchers adjusted those times four hours later, which was the equivalent of traveling westward across four time zones every day for a period of three weeks.

Jeanne Duffy, the co-author of the study, said that since the participants were “doing the equivalent of circling the globe every week,” their body’s internal clocks were unable to keep up and that it oscillated at its own pace. (Related: 10 Ways to Boost Your Metabolism Naturally.)

Because of this, the researchers were able to measure their metabolic rate during all different biological times of the day.

The results of the study revealed that resting energy expenditure was at its lowest at the circadian phase the researchers designated as -0 degrees, which corresponds to the dip in core body temperature in the late biological night. Energy expenditure was highest at circadian phase – 180 degrees at around 12 hours later, in the biological afternoon into evening.

The scientists shared that the volunteers’ respiratory quotient, which reflects macronutrient utilization, also changes by circadian phase. Their respiratory quotient was lowest in the evening and highest in the biological morning. The study results were the first to characterize a circadian profile in fasted resting energy expenditure and fasted respiratory quotient dissociated from the effects of activity, sleep-wake cycle, and diet in humans.

Duffy advised that what you eat and when you eat both affect how much energy you either burn or store as fat. She concluded that following regular eating and sleeping habits is crucial to your overall well-being.